The present invention relates to an antenna device for a mobile communication apparatus such as a mobile phone, PHS, cordless handset, and mobile data communications device, and to a mobile communication apparatus including the antenna device.
FIG. 21 and FIG. 22 are perspective views of mobile communication apparatuses equipped with conventional antenna devices, respectively. Mobile communication apparatuses 100 and 102 are equipped with respective antenna devices 101 and 103. The antenna device 101 is made from of a helical conductive wire, and the antenna device 102 is made from a linear conductive wire.
Since the conventional antenna device emits radio waves isotropically, about the device, a head of a user impedes the emitted radio waves when the user brings the mobile communication apparatus to his/her ear during using the apparatus. This reduces overall radiating efficiency of the device.
These conventional antenna devices are disclosed in the Japanese Laid-Open Patent Nos. 6-232622 and 10-313205.
An antenna device includes a radiator having a line length (L1) and a conductor having a line length (L2) smaller than the line length of the radiator. The conductor is disposed oppose to the radiator. Each line length satisfies the following formula:
L1=0.75xcexxc2x10.2xcex;
and
L2=0.25xcexxc2x10.2xcex,
where xcex is a wavelength of a signal applied to the radiator.